Carburetor



H. H. TlMlAN June 14,- 1932.

GARBURETOR Filed Feb. 25, 1929 2 Sheets-Sheet l .i 4 Af l l il. r /s w .n ...v

June 14, 1932. H. H. TIMIAN 1,862,585

' CARBUR'ETOR Filed Feb. 23, 1929 2 sheets-sheet 2 T f Vera L /.z arolcl fi Ja'ma'am j MM Patentedy `lune 14, 1932` UNITED STATES PATENT oFFIcE HAROLD E. .TIMIAN, F INDIANAPOLIS, INDIANA, ASSIGNOR T0 WHEELER-SCHEBLER OARBUBETER COMPANY, 0F INDIANAPOLIS, INDIANA, A CORPORATION OF INDIANA CARBUBETOR Application led February 23, 1929. Serial No. 342,097.

This invention relates to improvements in carburetors for internal combustion engines. It is an object of this invention to provide an improved form of plain tube carburetor embodyin an air bleed jet and throttle actuated acce erating pump acting on the fuel supplied to the normal fuel nozzles. It has heretofore been attempted to use a suction displacement type of accelerating fuel supply embodying air bleed jets and fuel wells, but this arrangement requires a variable time element to discharge and refill, depending upon the pressure conditions adjacent the fuel outlet. The quantity of fuel discharged is also subject to only slight pressure difference at the nozzle so that little or no control of the rate of discharge is possible.

It is accordingly an object of this invention to provide a carburetor of the type described wherein the fuel used for accelerating purposes is controlled directly from a throttle operated pump, thus assuring positive delivery or withdrawal of fuel in proportion to the throttle movement. It is another object of this invention to provide a fuel well filled by the operation of the accelerating pump and feeding into the carburetor through the air bleed nozzle. It is a further object of this invention to provide a simple form of plain tube carburetor that will have the power, range, and exibility required to meet operating conditions at a relatively low first cost accompanied by ease of service adjustments.

Other and further important objects of this invention will be apparent from the disclosures in the specification and accompanying drawings.

The invention (in a preferred form) is illustrated on the drawings and hereinafter more fully described.

@n the drawings Figure 1 is an elevation of .a carburetor with parts in section :to show features of the present invention as embodied therein.

Figure 2 is a section on the line ITL-Il o Figure 1. n

igure 3 is a 'fragmentary section on the line lila-111 et J igure 1 showing the idling it M engine.

Fig. 4 is a diagrammatic layout of the various fuel passages.

As shown on the drawings A carburetor body is shown as comprising an air inlet 10 leading to a vertical passage 11 having a venturi 12, and a throttle valve 13 therein, the valve 13 being mounted on a shaft 14, one end of which is provided with an operating lever 15 having an extra arm 16 carrying an adjustable screw 17. The Screw 17 engages a cam 18 on a rocker shaft 19, the cam in turn having a spring connection 20 to a choke valve operating lever 21, so arranged that when the choke valve is closed the cam is turned to crack open the main throttle valve to assist in starting the The other end of the rocker shaft 19 carries a lever 22 with a set screw 23A adapted to be enga ed by a cam 24 on the throttle shaft 14 when t e latter is turned to its wide open position. The cam 24 acts through the lever 22 to rock the shaft 19 which has a projecting pin 25 having a pilot engaging in an aperture 26 in a needle valve 27, the pin in turn lifting the valve 27. The pin 25 is intended to be made with various sized pilots to facilitate range and power settings in production, the aperture 26 being made large enough to receive a considerablv larger pilot. The lever 22 is also provided with a set screw 22a which forms the lean or idling range adjustment. y

The carburetor body incorporates the nsual oat bowl 29 which feeds through a port 30a into a vert-ical passage 30 opening into an accelerating pump chamber 31a light disc such as Celluloid being loosely pinned over the opening to form a iiap valve 82. From the chamber 31 the fuel Hows in a horizontal passage 33 leadin to a chamber 31 about 'the needle valve 2 and downwardly through a passage 35, controlled by the needle valve, into another horizontal passage 36 which leads into an inclined passage 37 extending to the main fuel nozzle 38, the outlet ofwhich is positioned at the throat of the venturi. The passages 33 and 36 are drilled from the surface of the body and are afterwards plugged as indicated by the numeral 11G, the lowermost plug 40 in Figure 1 showl@ ing the relationship of the passage 36 to the inclined passage 37 which can only be indicated in Figure 2 by the bottom sealing plug 41 therefor. A feed passage 42a extends from passage 33 to a vertlcal passage 42 which eX- tends upwards and is enlarged to form an open well 43 with a ball check 44 seating at the outlet of the passage 42. The well 43 is provided with an overfiow return 44a to the 'lo float bowl 29 as shown in dotted lines in Figure l, so that it can be filled only to a predetermined height.

An air bleed tube 46 extends from above the fuel level in the open well 43 to a passage 47 leading into the nozzle passage 37 below the nozzle, and this passage 47 is restricted by a plug 48 which is of course replaceable with another of a different size to vary the air bleeding effect. The tube 46 is apertured at 49 to allow the well to drain to the nozzle' through the air bleed tube.

The throttle shaft 14 carries a lever 50, associated with the cam 24, which lever is linked by a member 51 to an accelerating pump rod 52 carrying a piston 53 within the pump chamber. The end of a passage 54 is shown opening into the well pass'age 43 in Figure l and this passage 54 supplies fuel to a vertical passage 55 shown in Figure 3 whichis controlled by a cone pointed adjusting screw 56 and opens into the main carburetor passage 11 just above the edge of the throttle valve 13 when the latter is in its closed position as indicated by the numeral 57 This arrangement provides an adjustable fuel supply for idlin when the suction below the closed thrott e is insuii'cient to draw fuel from the main nozzle.

tion,.assuming that the engine is in normal operation the well will be emptied through the air bleed tube aperture 49 and the supply of fuel to the nozzle will be dependent upon the limited supply to the Well as well as upon the restricted passage 35 controlled by the needle valve, the light ila valve offering little resistance to upward ow of fuel.

When the throttle is opened the accelerating pump moves downwardly, seatin the ap valve and forcing fuel t rough a the passages beyond the valve, boththe main nozzle and idlin system discharging fuel while the well is llled at the same time. Un-

der conditions of sudden throttle operation the well overflows throu h the passage 44a to the float chamber to reIieve excessive pressures on the restricted fuel outlet. After the accelerating stroke of the pump the well o slowly drains back through the air bleed tube into the nozzle to supply the extra fuel required to sustain the acceleration until the intake manifold conditions again reach equilibrium.

05 The accelerating pump causes a fuel dis- In the illustrated embodiment of the invencharge in timed relationship to the demand and in proportion to the suddenness and extent of throttle opening, as contrasted to the suction displacement types of accelerating system which lag behind the demand and permit little orno control over the rate of discharge due to the slight pressure differences at the nozzle. With the arrangement of this invention the fuel is directly controlled by the throttle operated pump and very little fuel lies in the channels ad]acent the nozzle structure and an withdrawal or discharge of fuel follows t e pump action immediately. Upon a return of the pump piston from a displaced position the suction developed below the piston tends to momentarily withdraw or hold back fuel in the passages which provides for a very prompt drop in engine speed in response to a closing throttle.

It Y.will thus be seen that I have provided an improved plain tube carburetor having the desired power range and flexibility without undue complication. An important result ofthe new arrangement is to provide direct fuel pumping to the idler passages thus increasing the pressure thereon to carry over the normally lean eriod of transfer from the idling fuel. feedp to the main nozzle fuel feed upon sudden pick up from idling conditions or vice versa.

I am aware that numerous details of construction maybe varied through a wide range without departing from the principles of this invention, and I therefore d o not purpose limiting the patent granted, otherwise than necessitated by the prior art.

I claim as my invention z- 1. In a plain tube carburetor including the throttle valve and fuel metering system thereof, an acceleratin fuel pump directly operated by the thrott e and positioned in series with the normal fuel metering system, a fuel .well having a supply connection from said accelerating pump, an air bleed connection in said well leading to the fuel metering system, said air bleed connection being open to the atmosphere at one end and avmg an inlet thereto adapted to drain said well.

2. In a. plain tube carburetor including the throttle valve and fuel metering system thereof, an accelerating fuel pump directly operated bythe throttle and posltionedV in series with the normal fuel metering system, an open well having a supply connec tion' from said accelerating pump and having an overflow fuel return to the fuel supply source.

3. In,a carburetor of the class described, a throttle valve, an accelerating pump connected thereto to be operated thereby, a source of fuell suppl feeding into said pump, a nonreturn va ve on said fuel feed, a controllable valve in an outlet from said 13a pump, a fuel nozzle fed from said valve, means associated with said controllable valve for adjusting the same, means associated with said throttle adapted to Vary the position of said controllable valve in response to throttle movements. i

4. In a carburetor of the class described, a throttle valve, an accelerating pump connected thereto to be operated thereby, a source of fuel supply feeding into said pump, a nonreturn valve on said fuel feed, a controllable valve. in an outlet from said pump, a fuel nozzle` fed from said valve,v a choke valve and yielding means connecting i5 said choke valve to said controllable Valve adapted to vary the position of said valve when said choke valve is actuated.

5. In a carburetor of the class described, a throttle valve, an accelerating pump con- 20 nected thereto to be operated thereby, a.

source of fu'el supply feeding into said pump,

a. nonreturn valve on said fuel feed, a controllable valve in an outlet from said pump,

a fuel nozzle fed from sa-id valve, means for varying the position of said controllable valve, a earn associated with said throttle for actuating said means, a choke valve, and

yielding means associated therewith also adapted to actuate said means for varying the position of said valve.

6. In a plain tube carburetor, an idling passage and a mixing chamber a main nozzie discharging into the mixing chamber, a compensating air bleed connection to the main nozzle, a fuel Well surroundingsaid air bleed connection, a common fuel supply passage feeding said idler passage, main nozzle and said Well, and an accelerating pump in series with said fuel supply passage and adapted to increase the pressure on the fuel supplied to said idling passage as Well as to said nozzle and said well.

In testimony whereof I have hereunto subscribed my name at Indianapolis, Marion County, Indiana.

HAROLD H. TIMIAN. 

